Process for extracting sulfonic acids

ABSTRACT

SULFONIC ACIDS IN THE PRODUCT FROM A SULFOXIDATION REACTION ARE SEPARATED FROM SULFURIC ACID BY EXTRACTING WITH AT LEAST ONE ORGANIC SOLVENT THE HEAVY PHASE RESULTING FROM THE PROCESS REACTION. SUITABLE ORGANIC SOLVENTS INCLUDE HALOGENATED COMPOUNDS SUCH AS CARBON TETRACHLORIDE, CHLOROBENZENE AND ETHYLENE DICHLORIDE. FROM 400 TO 600% BY VOLUME OF SOLVENT IS USED, AND ROOM TEMNERATURE IS PREFERRED.

United States Patent 3,766,255 PROCESS FOR EXTRACTING SULFONIC ACID Henry Shuttleworth, Pointe-a-Pierre, Trinidad, West Indies, assignor t0 Texaco Trinidad, Inc., Point-a-Pierre, Trinidad, West Indies N0 Drawing. Filed Nov. 18, 1970, Ser. No. 90,790 Int. Cl. C07c 143/02 US. Cl. 260513 R 2 Claims ABSTRACT OF THE DISCLOSURE Sulfonic acids in the product from a sulfoxidation reaction are separated from sulfuric acid by extracting with at least one organic solvent the heavy phase resulting from the process reaction. Suitable organic solvents in clude halogenated compounds such as carbon tetrachloride, chlorobenzene and ethylene dichloride. From 400 to 600% by volume of solvent is used, and room temperature is preferred.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to a process for separating sulfonic acids from sulfuric acid with which they occur following a sulfoxidation process involving liquid hydrocarbons.

DESCRIPTION OF THE PRIOR ART In commonly assigned co-pending application, Ser. No. 40,740,fi1ed May 26, 1970, there is disclosed and claimed a process for producing sulfonic acids without irradiation 3,706,255 Patented Oct. 16, 1973 ice DESCRIPTION OF THE INVENTION A typical sample of the heavy product phase from the sulfoxidation process had the following characterization:

by reacting in a reactorsu-bstantially straight chain saturated liquid hydrocarbons with oxygen and sulfur dioxide under substantially anhydrous conditions in the presence of a low molecular weight acyl oxide such as acetic anhydride at temperatures of about to 55 C. under pressures of from 0 to 100 p.s.i.g. while agitating throughout the process these reactants followed by continuously removing the resulting heavy phase containing product and unreacted paraffins from the reactor.

The linear sulfonate product prepared by this process contains about 35 mole percent of sulfuric acid. Although this quantity of sulfuric acid is high, it has no detrimental effect in a finished detergent formulation containing such sulfonates, as the sodium sulfate formed from the sulfuric acid can be used as part of the builders in the detergent. Undesirably, however, it is not possible with this high a sulfuric acid content to obtain aqueous solutions of a neutral mixture at concentrations greater than w./ W. owing to the separation of sodium sulfate at room temperature. Thus it would be advantageous, with regards to increased facility in handling, improvement of minimum product value and appearance, if the sulfuric acid content could be reduced economically. Similarly, it would improve the economics of the process if the sulfuric acid could be made readily available for producing sulfur dioxide which could be used again in the sulfoxidation reaction.

SUMMARY OF THE INVENTION In accordance with the invention, the heavy product phase from the sulfoxidation process is extracted with from 300 to 600% by. volume of at least one organic solvent to remove the sulfonic acids present therein and leave behind sulfuric acid. Suitable organic solvents include halogenated compounds such as carbon tetrachloride, chlorobenzene, ethylene dichloride and mixtures thereof. The invention encompasses single and multiple contact extractions with single solvents and single contact extraction with double solvents.

To determine how effectively sulfonic acids are recovered from the heavy phase product by solvent extraction, the aniline method of analysis which is relatively easy and quick and which gives a quantitative comparison between the sulfuric and sulfonic acids contents of the experimental samples, was found to serve adequately.

Analysis of two 5 parts by vol. samples of the heavy phase product by this method gives an average value for Sulfonic acid/ sulfuric acid of 0.95 eq./eq.

(a) Single contact extractions with single solvents: Extractions were carried out batchwise. Small samples of heavy phase product and solvent were mixed thoroughly in a separating funnel and allowed to stand.

No phase separation was observed in mixtures of heavy phase product and any of the chosen solvents, carbon tetrachloride, trichloroethylene, chlorobenzene and ethylene dichloride, when the solvent dosage was less than 400% by volume of the heavy phase. At higher solvent dosages separation into two layers was observed. Comparative extractions were made with these solvents at dosages of 400% and 600%. In these extractions 5 parts by volume samples of heavy phase product Were mixed separately with 20 parts by volume and 30 parts by volume samples of the four solvents. In each case, two phases were observed; a small very dark layer which is rich in sulfuric acid, and a lighter layer which contains most of the sulfonic acids and the solvent. The relative positions of these layers depend on the density of the solvent used. Analytical data for these extractions are given in Table l. The figures given for the sulfonic acids concentration and recovery are calculated on the basis of the total acids (sulfuric and sulfonic) and disregard water, paraffin and solvent contents.

Chlorobenzene appears to give the best compromise for recovery and concentration of the sulfonic acids. Ethylene dichloride gives the best concentration but the recovery is somewhat lower than that of chlorobenzene.

(b) Triple contact extraction with a single solvent: Batchwise co-current triple contact extractions were carried out on 25 parts by volume samples of heavy phase product with the 4 solvents, with the aim of improving the sulfonic acids recovery over that obtained in the single contact extraction. In each extraction the heavy phase product was first contacted with 6 times its volume of solvent. In each of the next two contacting stages, the dark layer of the previous stage was contacted with 6 times and chlorobenzene were also carried out and in the case its volume of fresh solvent. Thus, a final dark layer or with trichloro'ethylene mixtures with the DMSO'at /2 and rafiinate phase, and 3 light layers or extract phases from 1 /2 times its original volume were also examined. The rethe 3 contacting stages are obtained. The extract phases sults are summarized in Table 3.

TABLE L-SINGLE CONTACT EXTRACTION OF HEAVY PHASE PRODUCT WITH SINGLE SOLVENTS AT ROOM TEMPERATURE Dark layer Light layer Potential RSOQII/ RSOQH RSOaI'I/ BS0311 recovery H 80 cone, HzSO cone, of BS0311, percent, percent, percent, percent, percent, Solvent Position eq./eq. eq./cq. Position eq./eq. eqJcq. cqJeq.

Solvent/heavy phase product, vol./vol.=6/1 o 0. 2 10 B 24 ottom. 2. 89 74 74 Top 0.123 2. 06 67 80 a 0. 108 2. 96 75 89 do 0. 150 7. 00 88 80 Solvent/heavy phase product, vol Carbon tet T p 0.375 27 ot 1. 82 65 79 Trichloroethylene 0. 194 1. 72 (i3 86 Ohlorobenzene 0. 106 1. 03 66 02 Ethylene dichloride do 0. 268 21 Top 3. 02 75 76 NOTEr-RSOaH concentration calculated on basis of total acids.

TABLE 2.TRIPLE CONTACT EXTRACTION OF HEAVY PHASE PRODUCT WITH SINGLE SOLVENTS AT ROOM TEMPER- ATURE, WITH SOLVENT DOSAGE OF 600% IN EACH STAGE Volume, ml. Dark layer Light layer Potential Solvent RSO3H/ RSOaH RSOfiI'I/ RSOrI-I recovery H2804, cone", H 804, conc oi RSOgH, Heavy Stage Stage Stage percent, percent, percent, percent, percent, Solvent phase 1 2 3 Position eq./eq. eq./eq. Position eq./cq. eq./eq. eq./eq.

Carbon tet 150 84 0. 094 2. 71 91 Tn'chloroethylene 25 150 45 0. 039 2. 00 67 96 Chlorobenzene 25 150 39 0.038 2. 88 74 95 Ethylene dichloride 25 150 46 0. 046 5.00 83 94 TABLE 3.SINGLE CONTACT EXTRACTION OI I HEAVY PHASE PRODUCT WITH DOUBLE SOLVENT AT ROOM EMPERATURE Dark layer Light layer Mixture composition volume Potential distribution RSOHHI BS0311 RSO H/ RSO H recovery H 804, cone, H 04, cone, of RSO H, Heavy Org. percent, percent, percent, percent,- percent, Organic solvent phase DMSO solv. Position eqJeq. eq./eq. Position eqJeq. eqJeq. eq./eq.

Trichloroethylene 1 1 0.103 9 Bottom 3 75 79 91 D 1 1 0.092 d 4 44 82 89 1 0.072 7 do 3 46 78 03 1 1% 0.072 7 do 3 47 78 93 1 1 0.108 10 Top 3 73 79 90 Do 1 1 0.125 4 46 82 87 Carbon tetrachloride 1 1 0.286 22 Bottom 3 64 78 67 were bulked, and aliquots of the dark layer and the bulked 45 What is claimed is: light layers were analyzed by the aniline method. The re- 1. Process for removing sulfonic acids from the prodsults are given in Table 2. net of a parafiin sulfoxidation reaction including a mix- Improved recovery of s-ulfonic acids was obtained in ture of water, unreacted paraflins, and sulfuric acid which each case, but there was a slight decrease in concentration. comprises extracting said product with 300 to 600% by Triple contact extractions where the extract phase 59 volume of one of a chlorinated solvent selected from the (light layer) from each contact stage was mixed with group of chlorobenzene, ethylene dichloride, carbon fresh solvent in the next stage at solvent dosages of 600% tetrachloride and trichloorethylene admixed with dimethwere also carried out with trichloroethylene and chloroyl sulfoxide inthe range of 3 to 6 parts of said chloribenzene. These gave a lower recovery and higher concennated solvent to /2 to 1 /2 parts of dimethyl sulfoxide tration of sulfonic acids than the single contact extracthereby forming a raflinate phase rich in sulfuric acid and tions. 1 an extract phase containing said sulfonic acid and solvent (c) Single contact extraction with double solvents: Exand separating said phases. traction of the heavy phase product with single solvent 2. The process according to claim 1, wherein the requires a very high solvent dosage (greater than 400%). amount of solvent used ranges from about 400 to about Single contact extractions were carried out, where 10 600 volume percent of said mixture. parts heavy phase product, 10 parts by volume dimethylsulfoxide (DMSO) and 30 parts by volume chlorinated References Cited organic solvents were mixed together. The organic sol- UNITED STATES PATENTS vents used were trichloroethylene, chlorobenzene and carbon tetrachloride. Separation into two layers occurred 3,423,454 1/1969 Marrian 260-5 13 R in each case. The analytical results are shown in Table 3. 3,454,479 7/1969 Hopkins et al. 260513 R Mixtures where the organic solvents content was re- 3,660,471 5/1972 Sawand et a1, 260- ,513 R duced to 10 ml. and lower showed little or no separation. v l I Extractions using higher dosages of trichloroethylenc DANIEL D. HORWITZ, Primary Examiner 

